Preheat oven to 200 degrees celsius (180 if using fan-forced).
Grease a large baking dish with butter and set aside.
Place peeled and sliced apples into the Thermomix bowl. Add the water, sugar, cinnamon, nutmeg and lemon juice. Cook for 5 minutes, 90 degrees REVERSE, Speed 1.
Drain the excess liquid from the apples and place into the prepared baking dish. Rinse and dry the Thermomix bowl.
Place the oats, flour, butter and sugar into the Thermomix bowl. Press Turbo a few times until you have achieved a consistent crumble mixture (and all of the dry ingredients have been completely combined with the butter.
Sprinkle the crumble over the apple and place into the preheated oven.
Cook for 35-40 minutes or until the crumble is golden and crunchy.
Serve immediately with ice-cream or cream.